今天给大家分享三种在ggplot2包画的图形上添加拟合的线性回归方程和R^2的值的方法。

1 解决方案1

library(ggplot2)
set.seed(1234)
df <- data.frame(x = c(1:100))
df$y <- 2 + 3 * df$x + rnorm(100, sd = 40)
p <- ggplot(data = df, aes(x = x, y = y)) +
  geom_smooth(method = "lm", se=FALSE, color="black", formula = y ~ x) +
  geom_point()
lm_eqn <- function(df){
  m <- lm(y ~ x, df);
  eq <- substitute(italic(y) == a + b %.% italic(x)*","~~italic(r)^2~"="~r2, 
                   list(a = format(unname(coef(m)[1]), digits = 2),
                        b = format(unname(coef(m)[2]), digits = 2),
                        r2 = format(summary(m)$r.squared, digits = 3)))
  as.character(as.expression(eq));
p1 <- p + geom_text(x = 25, y = 300, label = lm_eqn(df), parse = TRUE)
p1

运行结果，如图1所示。

2 解决方案2， 借用了 ggpmisc包 。

library(ggplot2)
library(ggpmisc)
set.seed(1234)
df <- data.frame(x = c(1:100))
df$y <- 2 + 3 * df$x + rnorm(100, sd = 40)
my.formula <- y ~ x
p <- ggplot(data = df, aes(x = x, y = y)) +
  geom_smooth(method = "lm", se=FALSE, color="black", formula = my.formula) +
  stat_poly_eq(formula = my.formula, 
               aes(label = paste(..eq.label.., ..rr.label.., sep = "~~~")), 
               parse = TRUE) +         
  geom_point()
p

运行结果，如图2所示。

3 解决方案3， 借用了 ggpurb包 。

library(ggplot2)
library(ggpubr)
set.seed(1234)
df <- data.frame(x = c(1:100))